In the past, direct converters, such as matrix converters, for example, were rather of academic importance. Nowadays, however, direct converters are gaining in importance in areas such as industrial applications. By means of a direct converter, an input voltage or an input current having a first amplitude and a first frequency can be converted directly into an output voltage or respectively into an output current having a second amplitude and a second frequency, without a complex DC voltage intermediate circuit or DC current intermediate circuit. Such a direct converter is disclosed in U.S. Pat. No. 6,900,998, for example, wherein the direct converter has n=3 input phase connections and p=3 output phase connections. In other words, the direct converter in U.S. Pat. No. 6,900,998 is embodied in a three-phase fashion on the input side and on the output side. The direct converter in U.S. Pat. No. 6,900,998 B2 also includes nine two-pole switching cells for switching a positive and a negative voltage between the poles, where each output phase connection is connected in series with each input phase connection directly via a switching cell, respectively.
However, in the direct converter according to U.S. Pat. No. 6,900,998, the voltage at each branch, i.e., at each two-pole switching cell, cannot be set in such a way that a continuous current flow from an input phase connection to an output phase connection can be obtained. As a result, it is not possible to achieve an active current setting through the respective branches. Furthermore, no or only a very limited exchange of electrical energy between individual branches is possible with the direct converter in U.S. Pat. No. 6,900,998. However, if the direct converter is intended to be able to transfer large amounts of electrical energy, then the capacitances of the switching cells in U.S. Pat. No. 6,900,998 B2 have to be implemented with correspondingly large dimensioning, which results in a huge space requirement for such a direct converter and considerable costs. As a result, systems constructed with direct converters of this type will likewise have a correspondingly large space requirement and be correspondingly expensive.